Compression ????

[LAMudbug]

Just wondering what the compression psi should be on a 155 hp evinrude. Done a check they all tested a 79 80 and 81.

 

[jonesg]

Re: Compression ????

Try a seafoam decarb treatment, see the faq files for the method, I just spray it right into the cylinder and run it, my compression came up 10psi.
Seafoam dissolves carbon on the piston rings.

But 80 psi is ok on big V6's.
2 strokes need to be decarbed every season, if enough carbon builds up the piston rings can get stuck and snap off on the port edges.

 

[tashasdaddy]

Re: Compression ????

is this a 55hp or 155hp???? off the top of my head i do not recall a 155.

 

[kenmyfam]

Re: Compression ????

155HP is news to me as well.

 

[emdsapmgr]

Re: Compression ????

OMC made a 155 in 1989-91 timeframe. It's a commercial model, which will have special components. Some of these models are made to run on a lower grade of fuel, so they may have somewhat lower compression than a normal consumer 150 model. I'd follow Jone's recommendation and do a decarb on the engine and see if the compression comes up any. If it doesn't change any, don't worry about it.

 

[jonesg]

Re: Compression ????

155HP is news to me as well.

Yeh I checked evinrude.com, 1990.
Think its a commercial like mine.
Bigger gearbox turning a bigger screw at lower rpm.

 

[LAMudbug]

Re: Compression ????

Yes I had to call Evinrude. It is a 88 or 89 155 hp super V6 it is actually a non production Military model the model is an AM 155 A Couldnt find any info anywhere but a rep at Evinrude got a little info. According to them it is compatible with the late 80s commercial models. Did a Decarb but have not checked the compression since. I know I have to do a carb rebuild too. just taking it one thing at a time

 

[kenmyfam]

Re: Compression ????

Yeh I checked evinrude.com, 1990.
Think its a commercial like mine.
Bigger gearbox turning a bigger screw at lower rpm.

Thanks for the education.